The present invention relates generally to an exhaust gas recirculation (EGR) system for regulating the flow of an exhaust gas.
EGR systems are increasingly being utilized to improve the efficiency of engines and reduce the harmful effects of the exhaust gas on the environment. As an engine burns fuel, it produces an exhaust gas which contains unburned fuel and other impurities. In an EGR system, the exhaust gas is redirected through the engine to burn any unburned fuel remaining in the exhaust gas. Reburning the exhaust gas before it is released reduces the harmful effects of the exhaust gas on the atmosphere and enables the vehicle to meet government emission standards.
In order to recirculate the exhaust gas, EGR systems typically include a valve and a cooler. The valve regulates the amount of exhaust gas that is introduced back into the engine. The cooler cools the exhaust gas to a specified temperature which condenses the unburned fuel.
Prior EGR systems utilize a vacuum source with a diaphragm actuator to open and close the valve. The diaphragm actuator has a slow response time and is either open or closed with no intermediate valve position. One drawback to the prior art is that the slow response time of valves reduce the horsepower and efficiency of the engine, limiting the amount the EGR system may be used.
Hence, there is a need for an improved exhaust gas recirculation system for regulating the flow of an exhaust gas.
The present invention relates to an exhaust gas recirculation system for regulating the flow of an exhaust gas.
The exhaust gas recirculation system includes an EGR valve apparatus which regulates the amount of exhaust gas that is recirculated in the system. In one embodiment, a motor rotates a shaft which opens or closes a plurality of valves. The amount of exhaust gas flowing through the EGR valve apparatus is proportional to the amount the valves are opened or closed.
In a second embodiment, a force balanced rotary EGR valve assembly including balance seat valves is utilized. When more exhaust is to enter a chamber, the shaft is rotated, moving a downward balanced seat rotary EGR valve downwardly out of the chamber against the flow of exhaust and an upward balanced seat rotary EGR valve upwardly into the chamber with the flow of exhaust. Rotating the shaft in the opposite direction reverses the movement of the valves, allowing less exhaust gas to enter the chamber.
A third embodiment includes an inline poppet located on each valve which opens to allow gas to enter the chamber before the EGR valve is opened to overcome the pressure in the system. A cam translates the rotary motion of the motor shaft to the linear motion of a valve shaft to open the EGR valve.
Alternatively, the motor rotates the motor shaft to pivot a balance arm in a fourth embodiment. A first end of the arm moves upwardly to raise an EGR valve, and a second end of the arm moves downwardly to lower an EGR valve, allowing more exhaust gas to enter the chamber. Reverse rotation of the shaft reverses the movement of the valves, allowing less exhaust gas to enter the chamber.
In a fifth embodiment, an air venturi apparatus is employed. The motor rotates a shaft of a poppet, separating a pintle from an orifice. The degree of separation of the pintle from the orifice allows a proportional amount of a fresh air/exhaust gas mixture to return to the system.
Accordingly, the present invention provides an exhaust gas recirculation system for regulating the flow of an exhaust gas.
These and other features of the present invention will be best understood from the following specification and drawings.